1. Technical Field
This invention relates to work holding fixtures, and more particularly to fixture brakes for rotatably positioning a work piece.
2. Discussion of the Background Art
When assembling certain large work pieces, it is highly desirable to have a fixture facilitating rotation of the work piece to desired angular positions. Motor vehicle instrument panels (IPs), for example, need to be worked on from both a front side, which is normally presented to the vehicle operator, and a back side, which is normally hidden from view once the IP is installed.
Known work holding fixtures used with IPs provide the desired rotation of the IP about a lateral axis. However, it is further desired to be able to easily transfer IPs from shipping racks to the work fixtures, or vice-versa. Known fixtures do not adequately facilitate this type of transfer.
It is therefore desired to provide a mechanism which facilitates the easy movement of an IP to and from a shipping rack relative to a work fixture while enabling rotation of the IP in the work fixture.
A work holding fixture includes a support frame having a first and a second side member. The first and second side members are connected by a connecting member. Fixed to the first side member is a fixture brake, with a shaft rotatably mounted relative to the first side member. A brake barrel assembly is mounted to one of the first and second side members. The brake barrel assembly has a barrel portion fixed to one of the first and second side members, and has a backing plate rotatably mounted to the one of the first and second members, and is in axial alignment with the fixture brake shaft. The backing plate has a feature which slidably receives a first bracket. The first bracket is configured for attachment to a work piece received by the backing plate. A tail stock assembly, with a drum portion and a bracket guide, is rigidly mounted to the other of the first and second side members. The tail stock assembly slidably receives a second bracket. The second bracket is configured for attachment to a work piece received by the tailstock assembly.
The brake barrel assembly may also have a spring loaded detent device mounted to one side for locking engagement with the backing plate.
The drum portion may include a guide positioned for receipt and rotation of the second bracket. The drum portion may also contain an opening at one end with a bracket guide extending from the opening. The bracket guide is used as a funnel for receipt and rotation of the second bracket. A roller pocket guide maybe positioned in the drum portion such that a radial gap of a predetermined size exists between the outer diameter of the roller pocket guide and inner diameter of the drum portion. The second bracket may also have rollers mounted thereto for receipt and rotation in the roller pocket guide. The roller pocket guide allows for ease in rotation.
A brake barrel assembly includes a barrel portion with an axially extending arcuate wall and a receiving slot through the wall. A backing plate is rotatably connected to the barrel portion and has a slot feature which slidably receives a bracket. The bracket is configured for attachment to a work piece that is received by the backing plate. The slot feature is aligned with the receiving slot when in the first position. A spring loaded detent device is mounted on one side of the brake barrel lockingly engaging the backing plate in a first position.
The spring loaded detent device may also contain a plunger assembly. The plunger assembly has a plunger housing that is mounted to the brake barrel assembly, a plunger roller tip that is received by a notch in the backing plate in the first position, and, a plunger spring which biases the plunger roller tip into engagement with the notch.
The slot feature may be further defined by two slot brackets that are configured for attachment to the backing plate. The slot brackets may also have chamfered surfaces that extend outwardly from the slot feature into approximate alignment with the receiving slot facilitating receipt of the bracket. A sliding bracket may be disposed in the slot feature and sized for a slidable fit between the slot brackets. The sliding bracket has a first end in approximate alignment with the inner diameter of the barrel portion to maintain the relative position of the sliding bracket and the slot brackets with rotation of the backing plate.
A work holding fixture in accordance with the present invention represents a significant improvement as compared to conventional work holding fixtures. The present invention allows for easy rotation of the work piece to desired angular positions. The present invention also allows for easy transfer from shipping racks to work fixtures, or vice-versa.
These and other features and objects of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.